Scroll Compressor

ABSTRACT

A scroll compressor is provided which has favorable assembling property, does not require a thrust bearing, has a bearing structure for bearing a compression section at both sides thereof and has a simple structure of a scroll. The scroll compressor includes a compression section  3  constituted of an orbiting scroll  31  which is provided in a closed container  1,  and in which volutes are substantially symmetrically formed on both surfaces of an orbiting base plate  31 B, and a main shaft  7  is penetrated through and fixed to a center portion thereof, and a pair of fixed scrolls  33  and  34  that have the main shaft penetrated through and are placed on both the surfaces of the orbiting scroll, and have volutes which correspond to the respective volutes to respectively form compression chambers  32,  and a motor  2  which is provided in the closed container and drives the main shaft, and the main shaft has a notch part  71  which is formed at a portion penetrating through the orbiting scroll and fixed scrolls, and a slider is provided, the slider having eccentric hole including a flat slide surface corresponding to the notch part, the slider being fitted to the main shaft where the notch part is formed, and the slider being made slidable in a direction orthogonal to a length direction of the main shaft by the flat slide surface, and balancers, for canceling imbalance associated with eccentric orbiting movement of the orbiting scroll, are fitted to the main shaft at both sides of the compression section.

TECHNICAL FIELD

The present invention relates to a scroll compressor, and moreparticularly to a scroll compressor having volute teeth on both surfacesof a base plate of an orbiting scroll.

BACKGROUND ART

In a conventional scroll compressor, for example in a case of a verticaltype scroll compressor, an orbiting scroll has volute teeth formed onboth surfaces of an orbiting scroll base plate, and compression chambersare formed on an upper and a lower surfaces of the orbiting scroll byopposing a pair of fixed scrolls to the respective volute teeth. Theorbiting scroll is driven by a shaft penetrating through each of thescrolls. In this case, a penetrating shaft has an eccentric shaftportion, and the eccentric shaft portion is supported by bearing at apenetrating hole of the orbiting scroll base plate for driving androtating the orbiting scroll. Bearing formed at each penetrating hole ofthe two fixed scrolls supports the coaxial portions of the shaft at bothsides of the orbiting scroll. (see for example, Japanese PatentLaid-Open No. 08-70592)

Patent Document 1: Japanese Patent Laid-Open No. 08-170592

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The conventional scroll compressors are constructed as described above.In particular, in Patent Document 1, the eccentric distance of theeccentric shaft portion must be adjusted to form small compressionchambers between side surfaces of volute teeth of the orbiting scrolland opposite side surfaces of the fixed scrolls. In this case, operatingfluid may might leaked from between the opposing side surfaces of thevolute teeth an hence deteriorated the function. Hence, cost tends tobecome high to precisely machine the eccentric distance of the eccentricshaft portion and to precisely assemble the portions.

Further, leakage of the operating fluid may seriously damage theperformance in case the refrigerant has small molecular weight such asCO₂ refrigerant or in case the refrigerant needs large pressuredifference than conventional fluorine refrigerant.

The present invention is made to overcome the above described problems,and has an object to provide a scroll compressor that has favorableassembling property, that improves leakage of the operating fluidbetween volute teeth, and that has improved sealing and bearingstructure.

Means for Solving the Problems

A scroll compressor according to the present invention comprises acompression section provided in a closed container, the compressionsection including an orbiting scroll and a pair of fixed scrolls. Theorbiting scroll has volute teeth formed substantially symmetrically onboth surfaces of an orbiting base plate, and a main shaft is penetratedthrough and fixed at a center portion of the orbiting scroll. The pairof fixed scrolls is opposed to the both surfaces of the orbiting scrolland supports the main shaft by bearing action. Each of the fixed scrollshas volute teeth corresponding to each of the volute teeth of theorbiting scroll to respectively form compression chambers. A motor isprovided in the closed container for driving the main shaft, and themain shaft has a notch part at a portion penetrating through theorbiting scroll and fixed scrolls. Further, a slider is provided thathas an eccentric hole including a flat slide surface corresponding tothe notch part, and is fitted to the main shaft where the notch part isformed. The slider is made slidable in a direction orthogonal to alength direction of the main shaft by the flat slide surface.

Further, a pair of balancers is fitted to the main shaft at both sidesof the compression section for canceling imbalance associated witheccentric orbiting movement of the orbiting scroll,

Advantages of the Invention

The scroll compressor according to this invention is constructed asdescribed above. Accordingly in case of assembling a vertical type, forexample, the compression section is placed in a lower space of thecontainer, the motor is placed in an upper space, and a glass terminalcan be provided at an upper end portion above the motor. Therefore,after the compression section and the motor are all fixed inside thecontainer, a lead wire can be finally connected to the terminal, andtherefore, assembling property is improved.

Further, the substantially symmetrical volute teeth are formed on bothsurfaces of the orbiting scroll and the thrust loads caused bycompression of an operating gas are cancelled by each other so that athrust bearing does not have to be provided.

Accordingly, it can be prevented that an increase in abrasion loss andburning due to a broken oil film occurs due to its low circumferentialspeed and difficulty in forming oil film, that is caused in case ofthrust bearing using a gas such as CO₂ gas at high pressure with a highload.

Further, since the compression section is supported by bearing structureon both sides thereof, a moment does not occur to the shaft, andtherefore, one-side abutment on the bearing due to tilt of the shaft maybe prevented, and an associated increase in bearing loss and burning maybe prevented.

Further, as described above, the volute teeth on both surfaces of theorbiting scroll are formed to be substantially symmetrical and havesubstantially the same heights, and therefore, they are simple instructure and can be formed easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing one example of an entireconstruction in the case of using a vertical container according to afirst embodiment;

FIG. 2 shows a construction of an orbiting scroll in the firstembodiment, (a) is a sectional view, (b) is a plane view showing aconstruction of the upper, and (c) is a plane view showing aconstruction of the lower surface;

FIG. 3 shows a construction of a core part located in a center portionof the orbiting scroll shown in FIG. 2, (a) is a perspective view, (b)is a perspective view showing a construction of a seal ring eachprovided at an upper surface and a lower surface;

FIG. 4 is an explanatory sectional view for explaining an operationaleffect of the seal ring in the core part;

FIG. 5 shows the construction of a fixed scroll at the lower side inFIG. 1 of the fixed scroll s in the first embodiment, (a) is a planeview, and (b) is a sectional view taken along the line A-A in (a);

FIG. 6 is an enlarged view of the penetration structure of the mainshaft and the compression section and the structure of the lower endportion of the main shaft;

FIG. 7 is an explanatory view to show relation of the orbiting movementof the orbiting scroll and compression chambers.

FIG. 8 shows a perspective view of the construction of a main shaft anda slider in the first embodiment of the present invention.

FIG. 9 is an explanatory view for explaining the operation principle ofthe slider in the first embodiment.

FIG. 10 is a perspective view showing the construction of a firstbalancer in the second embodiment of the present invention.

FIG. 11 is a perspective view showing the construction of a secondbalancer in the second embodiment of the present invention.

FIG. 12 is an explanatory view for explaining the operational effect ofeach of the balancers in the second embodiment.

EXPLANATION OF THE REFERENCE NUMERALS

1 closed container, 2 motor, 3 compression section, 4 lubricating oilstorage chamber, 5 suction pipe, 6 glass terminal, 7 main shaft, 8discharge pipe, 9 first balancer, 31 orbiting scroll, 31A core part, 31Borbiting base plate, 31D orbiting bearing, 31E seal ring groove, 31Fabutment joint, 31G seal ring, 31H tip seal groove, 31J Oldham groove,31K communication port, 32 compression chamber, 33 upper fixed scroll,33B main bearing, 34 lower fixed scroll, 34A fixed base plate, 34C mainbearing, 34D recessed portion, 34E volute tooth, 34F discharge port, 34Gdischarge passage, 34H discharge valve, 34J suction port, 35 Oldhamjoint, 71 notch part, 72 slider, 72A flat slide surface, 72B eccentrichole, 76 oil feed pump, 77 lubricating oil, 78 second balancer, 91fitting hole, 92 cylindrical body, 93 projected part, 94 flange portion.

BEST MODE FOR CARRYING OUT THE INVENTION

First, the construction of a compressor, which is a basis of thisinvention, will be described based on the drawings. FIG. 1 is aschematic sectional view showing one example of an entire constructionusing a vertical container according to the first embodiment, FIG. 2shows a construction of an orbiting scroll in the first embodiment, (a)is a sectional view taken along the line A-A in (c) that will bedescribed later, and the left side shows an upper surface while theright side shows a lower surface. (b) is a plane view showing aconstruction of the upper surface of the orbiting scroll, and (c) is aplane view showing a construction of the lower surface of the same.

FIG. 3 shows a construction of a core part located in a center portionof the orbiting scroll shown in FIG. 2, (a) is a perspective viewshowing the shape of the core part, (b) is a perspective view showing aconstruction of a seal ring each provided at an upper surface and alower surface of the core part, FIG. 4 is an explanatory sectional viewfor explaining an operational effect of the seal ring in the core part,FIG. 5 shows the construction of a lower side fixed scroll in FIG. 1 inthe first embodiment, (a) is a plane view, and (b) is a sectional viewtaken along the line A-A in (a).

In a scroll compressor of FIG. 1, a motor 2 is placed at an upperportion in a vertical closed container 1, a compression section 3 isplaced in a lower portion, and a lubricating oil storage chamber 4 isformed under the compression section 3.

A suction pipe 5 is provided for sucking a suction gas in the closedcontainer 1 at an intermediate portion between the motor 2 and thecompression section 3, and a glass terminal 6 is provided at an upperend of the closed container 1 at the upper side of the motor 2.

The motor 2 is constructed by a known stator 21 formed into a ringshape, and a rotor 22 supported to be rotatable in the inside of thestator 21. A main shaft 7 is fixed to the rotor 22, and the main shaft 7penetrates through the compression section 3 to extend to thelubricating oil storage chamber 4. The relationship between thecompression section 3 and the main shaft will be described later.

The compression section 3 includes an orbiting scroll 31 having voluteteeth formed on an upper surface and a lower surface of an orbiting baseplate in substantially symmetrical shape with substantially sameheights, an upper fixed scroll 33 which is disposed to be opposed to theupper surface of the orbiting scroll 31 and has an invlute tooth whichcorresponds to the upper surface volute tooth of the orbiting scroll 31to form a compression chamber 32, a lower fixed scroll 34 which isdisposed to be opposed to the lower surface of the orbiting scroll 31and has a volute tooth which corresponds to the lower surface volutetooth of the orbiting scroll 31 to form the compression chamber 32, anda known Oldham joint 35 which is placed between the lower fixed scroll34 and the orbiting scroll 31.

The detailed construction of the orbiting scroll 31 will be describedwith reference to FIG. 2. As shown in this drawing, the orbiting scroll31 has a core part 31A which forms a center portion and is constitutedof a curved line such as an arc, and a disk-shaped orbiting base plate31B which extends on the outer periphery of the core part 31A.

As shown in the enlarged view of FIG. 3( a), in the core part 31A, ahole 31C, through which a main shaft 7 penetrates, is formed in a centerportion, and an orbiting bearing 31D is provided on its inner peripheralwall. A seal ring groove 31E is respectively formed on both surfaces ofthe core part at an outer side of the orbiting bearing 31D, and a sealring 31G having an abutment joint 31F as shown in FIG. 3( b) is insertedin a respective groove. The details of the seal ring 31G will bedescribed later.

In the core part 31A, a volute tooth is usually formed in an involutecurve or an arc outward from its center, and the number of turns of thevolute tooth is proportional to the compression ratio of the compressor.In the case of using an HFC gas in air-conditioning for example, thecompressor is operated at the compression ratio of 3, so that the numberof turns of the volute tooth needs to be three or more. But in the caseof using a CO₂ gas with a low compression ratio, the compressor isoperated at the compression ratio of 2, so that the number of turns ofvolute tooth becomes two or more, and thus it is possible to reduce thenumber of turns of the volute tooth by one turn as compared with thecase of the HFC gas.

Accordingly, by decreasing the turns of the volute tooth by the amountof one turn or more at the center portion, it becomes possible to formthe hole 31C in the center portion of the core part 31A for penetratingthe main shaft and to provide the orbiting bearing 31D.

This can be applied for any other case where the low compression ratiois a rated condition as well as the case of CO₂ gas.

Two or more turns of a volute tooth are formed respectively on the uppersurface and the lower surface of the orbiting base plate 31B in involutecurves or arcs substantially symmetrically and substantially in the sameheight as the core part.

“Substantially symmetrical” means that the thickness t, height h, pitchp and the numbers of turns n of the volute tooth shown in FIG. 2( a) aresubstantially equal, and thereby, the reaction force in the thrustdirection which occurs at the time of gas compression is made completelyor substantially equal.

Therefore, the thrust forces, which act on the orbiting scroll 31 toupward and downward direction at the time of compression, are cancelledout, and the load in the thrust direction becomes substantially zero, sothat the thrust bearing can be eliminated.

Since the thrust forces can be cancelled out by each other, the toothheight of the scroll can be made low, and the volute may be enlarged inthe diameter direction into a so-called thin pancake shape, whereby theradial direction force can be made relatively small, and reliability ofthe journal bearing can be enhanced.

The volute teeth on the upper surface and the lower surface are madesubstantially symmetrical, but in actual a slight difference is made tooccur in the gas pressures of the upper and lower compression chambersfor example in order to give rise a slight thrust force downwardly.

As a result, the volute tooth at the lower side of the orbiting scroll31 is brought into pressure contact with the lower fixed scroll 34, andthe volute tooth at the upper side has a gap from the upper fixed scroll33. Therefore, in the volute tooth of the upper side, a tip seal groove31H is formed at the upper end surface of the volute tooth as shown inFIGS. 2( a) and (b), and a tip seal 36 (FIG. 6) is fitted inside of it.On the lower side of the orbiting scroll 31, an Oldham groove 31Jcorresponding to the Oldham joint 35 is formed at an outermostperipheral portion.

The seal ring 31G provided at the core part 31A is formed as a ringwhich is rectangular in section as shown in FIG. 3( b) and has theabutment joint 31F, and is fitted in the seal ring groove 31E shown inFIG. 3( a). This seal ring 31G is placed in the core part 31A toseparate the main shaft 7 and the orbiting bearing 31D from the centerside of the volute tooth in order to prevent leakage therebetween, sinceat the time of a compressing operation, the main shaft 7 and theorbiting bearing 31D are at a low pressure, while the center side of thevolute tooth is at a high pressure.

The separating action is performed by contact sealing of the seal ring31G by pressure difference. The seal ring 31G is pressed against theright side wall and to the upper side fixed scroll 33 in the seal ringgroove 31E being pressed from the high pressure left side and the lowerside as shown by the arrow in FIG. 4.

In this case, sliding contact occurs at the surface of the fixed scroll,but the sliding is at a low circumferential speed of a grinding motionin a small radius as the tip seal, and therefore, friction and slidingloss are small.

In the core part 31A, a communication port 31K is formed at the outerside of the seal ring groove 31E. The communication port 31K penetratesthrough the orbiting base plate 31B in the vertical direction andcombines the gases, which are compressed in the compression chambers onboth surfaces of the orbiting scroll 31 as will be described later, toflow to a discharge port of the fixed scroll.

The communication port 31K is formed as a long hole along the seal ringgroove 31E, or is formed as a plurality of holes disposed adjacentlyeach other to perform substantially equivalent action as the long hole,and is provided at the position which is not across the compressionchambers, and always communicates with the discharge port of the fixedscroll, that will be described later.

Next, the detailed construction of the fixed scroll will be describedwith reference to FIG. 5. FIG. 5 shows one example of the lower fixedscroll 34.

As shown in FIGS. 5( a) and (b), a hole 34B is formed in a centerportion of a fixed base plate 34A through which the main shaft 7penetrates, and a main shaft bearing 34C is provided on an innerperipheral surface of this hole.

A recessed portion 34D is formed in the peripheral portion of the mainshaft bearing 34C, i.e. the center portion of the fixed base plate 34A,and accommodates the core part 31A of the orbiting scroll 31 and allowsthe orbiting movement of the orbiting scroll 31. At the outer peripheryof the recessed portion 34D, a volute tooth 34E is formed in two or moreturns in the same size as the volute tooth of the orbiting scroll 31 inthe volute curve or the arc but is rotated 180 degrees in phase.

A discharge port 34F is provided in the recessed portion 34D fordischarging the compressed gas without crossing the seal ring 31G of theorbiting scroll.

The discharge port 34F is formed as a long hole along an inner side ofthe innermost volute tooth of the fixed scroll, or is formed as aplurality of holes disposed adjacently each other to performsubstantially the equivalent action with the long hole, and is providedat the position which always communicates with the communication port31K of the orbiting scroll.

Further, a discharge passage 34G is formed which communicates with thedischarge port 34F and flows the compressed gas out of the compressorvia a discharge pipe 8 (FIG. 1). A discharge valve 34H is placed at aposition opposed to the discharge port 34F in the discharge passage 34Gas shown in FIG. 1, and prevents a backflow of the discharge gas.

In an outermost peripheral portion of the lower fixed scroll 34, asuction port 34J is provided as a suction inlet of the suction gas tothe lower compression chamber. A discharge port 34K (FIG. 1) is providedwhich communicates from the suction port 34J to the lubricating oilstorage chamber 4 at the lower portion of the closed container. A checkvalve 34L is provided for the discharge port 34K at the side of thelubricating oil storage chamber 4 as shown in FIG. 1.

The check valve 34L is provided to prevent that oil foams with remainingrefrigerant and flows out of the compressor when actuating thecompressor. The suction path for suctioning gas into the compressionchamber is formed as shown by the broken line arrow G in FIG. 1. Thesuction path includes the suction port 33A formed in the outermostperipheral portion of the upper fixed scroll 33 and the suction port 34Jof the lower fixed scroll 34, and the suction gas is introduced into therespective compression chambers formed both on the upper surface and thelower surface of the orbiting scroll 31.

As shown in FIG. 1, the upper end portion of the main shaft 7 is fittedinto the rotor 22 of the motor 2. The main shaft penetrates thethrough-hole of the upper fixed scroll 33, the through-hole 31C of theorbiting scroll 31 and the through-hole 34B of the lower fixed scroll 34and is immersed at its lower end portion in the lubricating oil 77 inthe lubricating oil storage chamber 4.

FIG. 6 shows an enlarged view of the penetration structure of the mainshaft 7 into the compression section 3 and the structure of the lowerend portion of the main shaft 7. Namely, a main shaft bearing 33B isprovided between the main shaft 7 and the upper fixed scroll 33. On thesurface of the main shaft 7, a notch part 71, having flat surface, isformed from the portion in contact with the main shaft bearing 33B downto the lower end. A slider 72, having an eccentric hole (not shown) witha partially flat surface corresponding to the notch part 71, is fittedto the notch part 71 of the main shaft 7. The outer peripheral surfaceof the slide 72 is placed to be in contact with the inner peripheralsurface of the orbiting bearing 31D of the orbiting scroll 31 shown inFIG. 2. The slider 72, forming an eccentric shaft in combination withthe main shaft, drives the orbiting scroll 31 via the orbiting bearing31D.

On the upper and the lower surfaces of the slider 72, recesses 73 areformed for the paths of lubricating oil. On the surface of the outerperipheral portion of the slider 72, which is in contact with theorbiting bearing 31D, an oil feed groove 74 is formed in the verticaldirection and allows the recess 73 on the upper surface to communicatewith the recess 73 on the lower surface.

In main shaft 7, an eccentric oil feed hole 75 is formed and extendedfrom the lower end to reach the main shaft bearing 33B of the upperfixed scroll 33. An oil feed pump 76 is provided at. the lower end ofthe main shaft 7 and is immersed in lubricating oil 77 at the lower endof the closed container 1.

Next, an operation of the first embodiment will be explained.

The gas, which is sucked into the closed container 1 from the suctionpipe 5, flows into a part of the motor 2. After cooling the motor 2, thegas is taken into the compression chambers 32 on the upper and lowersurfaces of the orbiting scroll 31 from the suction port 33A provided inthe outer peripheral portion of the upper fixed scroll 33 as shown bythe broken line arrow G.

Thereafter, the orbiting scroll 31 performs orbiting movement, withoutrotating around its own axis, with respect to the upper and the lowerfixed scroll s 33 and 34. A pair of crescent compression chambers, whichare formed by the known compression principle, reduce their volumesgradually toward the center. The pair of compression chambers finallycommunicate with each other in the innermost chambers in which thedischarge port 34F is present, and flows are guided outside thecompressor through the discharge passage 34G.

FIG. 7 shows the process in which a pair of crescent compressionchambers, which are formed by the orbiting movement of the orbitingscroll 31, gradually reduce their volumes toward the center. FIG. 7( a)shows the state of the orbiting scroll 31 at the orbit angle of 0°. Thediagonally slashed portion represents the volute tooth of the orbitingscroll, and the portion painted in black represents the volute tooth ofthe fixed scroll.

In the state of FIG. 7( a), the compression chambers at the outermostperiphery complete containing of the gas, and a pair of crescentcompression chamber A and B are formed. FIG. 7( b) shows the state inwhich the orbiting scroll 31 orbits by the orbit angle of 90° in thecounterclockwise direction.

A pair of compression chamber A and B moves toward the center whilereducing in volume.

FIG. 7( c) shows the state of the orbit angle of 180°, and FIG. 7( d)shows the state of the orbit angle of 270°. In this state, thecompression chambers A and B communicate with each other in theinnermost chamber in which the discharge port 34F is present, and thegas is discharged from the discharge port 34F.

In FIG. 7, the shape of the core part 31A of the orbiting scroll 31forms the volute curve up to the portion shown by the broken line, andforms one border of the compression chamber B. The center side from thisbecomes the curve of the core part and forms the innermost chamber thatdoes not contribute to compression, and forms a border surface incombination with the inner surface of the volute tooth of the fixedscroll 34.

The discharge port 34F is provided in the innermost chamber which doesnot contribute to compression, and is positioned not to cross theaforementioned seal ring 31G during the compression step, so that asufficient flow passage is ensured. For that purpose, the curve of thecore part and the curve of the inner surface of the volute tooth of thefixed scroll are formed to secure a clearance space in order not toblock the discharge port 34F completely with the core part 31A duringthe compression step.

In a type of compressor in which an integrated volume ratio is fixed asa scroll compressor, compression insufficiency loss occurs in the finaldischarge step when the operation is performed with a higher compressionratio than a set compression ratio. The compression insufficiency lossmeans that the pressure in the innermost chamber is higher than thepressure of the compression chambers A and B, when the innermost chamberand the compression chambers A and B communicate each other as in FIG.7( d) for example. Then, backflow occurs to the compression chambers Aand B from the innermost chamber, and causes loss of the compressionpower.

Therefore, the top clearance volume is restrained to a minimum, which isdefined as the volume upstream of the discharge valve 34H, namely thetotal sum of the innermost chamber, the discharge port 34F and thecommunication port 31K. Further, a little relief portion 34M is formedin the core part 31A. The relief portion 34M is to secure a flow passageby expanding width with reduced radius of the curvature.

Next, oil feed will be described. As shown in FIG. 6, the lubricatingoil 77, which is sucked as shown by the arrow from the lower end of themain shaft 7 by the oil feed pump 76, is sucked up through the oil feedhole 75 in the main shaft 7 as shown by the arrow, and is fed into themain shaft bearing 33B of the upper fixed scroll 33.

Thereafter, the lubricating oil passes the flat portion of the notchpart 71 formed on the main shaft to flow down and, via the recess 73formed on the upper surface of the slider 72, flows into the oil feedgroove 74 which is formed in the vertical direction on the outerperipheral surface of the slider 72 to lubricate the slider 72.

The oil, which flowed down in the oil feed groove 74, passes via therecess 73 on the lower surface of the slider, and passes through areturn hole 34N formed in the lower fixed scroll 34, and flows towardsthe center direction of the main shaft, and flows down in the notch part71 of the main shaft 7 again while feeding oil to the main shaft bearing34C of the lower fixed scroll 34, and is discharged outside the mainshaft from the lower end portion of the main shaft bearing 34C as shownby the arrow, and returns to the lubricating oil storage chamber 4.

As described above, the oil feed path forms a circulating closed loopfrom feeding through discharging without directly contacting the flow ofthe suction gas.

Accordingly, it is prevented that the oil is caught by the suction gasand flows out of the compressor.

The compressor is constructed as above, and therefore the compressor issuitable, for example, in a case where a heat exchanger volume of an airconditioner is made large for energy saving, in a case where theapparatus is tuned to perform a normal operation with a low compressionratio as an ice thermal storage system for peak-cut and load-leveling,and in a case where a refrigerant such as a CO₂ gas is used and normaloperation is performed at a low compression ratio for air conditioningoperation. A high efficiency of the apparatus can be maintained.

FIRST EMBODIMENT

Hereinafter, a first embodiment of the present invention will bedescribed with reference to the drawings. FIG. 8 shows the constructionof a main shaft and a slider in the first embodiment, (a) is aperspective view showing the construction of the main shaft, and (b) isa perspective view showing the construction of the slider. FIG. 9 is anexplanatory view for explaining the operation principle of the slider.The entire construction of the compressor is the same as FIG. 1, andtherefore, duplicated illustration thereof will be omitted.

With regard to the main shaft 7 shown in FIG. 8( a), the right end sidein the drawing corresponds to the upper side in FIG. 1, and the left endside of the drawing corresponds to the lower side in FIG. 1.

The notch part 71 forms a flat surface on the lower portion of the mainshaft 7, and this notch part 71 is formed from the portion in contactwith the main shaft bearing 33B of the upper fixed scroll 33 down to thelower end of the main shaft as described in FIG. 6.

As shown in FIG. 8( b), the cylindrical slider 72 is prepared that hasan eccentric hole 72B and a slider surface 72A corresponding to thenotch part 71. The notch part 71 of the main shaft 7 is fitted into theeccentric hole 72B of this slider so that the slide surface 72A and thenotch part 71 correspond to each other, and the slider is penetratedthrough the through-hole 31C of the orbiting scroll 31 as shown in FIG.6, so that the outer peripheral surface of the slider 72 is in slidingcontact with the inner surface of the orbiting bearing 31D.

As for the outside diameter of the main shaft 7 and the inside diameterof the eccentric hole 72B of the slider 72, the outside diameter of themain shaft is set to be a little smaller, as a result of which, thenotch part 71 and the slide surface 72A can slide a little parallel witheach other.

The operation principle of the slider 72 will be described withreference to FIG. 9. As shown in FIG. 9( a), the center of the slider 72is set as the same as a center 31X of the orbiting scroll 31, and thecenter of the main shaft 7 is set to correspond to a center 34X of thefixed scroll. Therefore, the center of the slider 72 is eccentric withrespect to the center of the main shaft 7 by “r” corresponding to thecrank radius, which is equal to the distance by which the volute toothof the orbiting scroll 31 and the volute teeth of the fixed scrolls 33and 34 idealistically rotate in contact with each other.

When the main shaft 7 rotates, the orbiting scroll 31 generates acentrifugal force, and the force acts in the direction shown by Fc inFIG. 9( a). On the other hand, a reaction force Fg by the gas pressureoccurs in the orthogonal direction to this, and therefore, the slider 72presses the slide surface 72A to the notch part 71 of the main shaft 7,and slides in the Fc direction.

As a result, as shown in FIG. 9( b), the volute tooth 34E of the fixedscroll and the volute tooth 31M of the orbiting scroll contact eachother and slide until a contact reaction force FR, which is balancedwith Fc, occurs, and therefore, contact sealing between the volute teethof the fixed scroll and the orbiting scroll is realized.

Since the contact sealing between the volute teeth is made by the slider72 like this, leakage between the volute teeth is restrained to theminimum and a scroll compressor with high compression efficiency can beobtained.

Especially when a gas, which has a large pressure difference and easy toleak such as a CO₂ gas, is used, the slider 72 is indispensable.

SECOND EMBODIMENT

Next, a second embodiment of this invention will be described withreference to the drawings. FIG. 10 is a perspective view showing theconstruction of a first balancer in the second embodiment, FIG. 11 is aperspective view showing the construction of a second balancer in thesecond embodiment, and FIG. 12 is an explanatory view for explaining theoperational effect of each of the balancers. The entire construction ofthe compressor is the same as in FIG. 1, and the duplicated illustrationthereof will be omitted.

FIG. 10 shows the construction of a balancer for canceling imbalanceassociated with the eccentric orbiting movement of the orbiting scroll.In the second embodiment, two balancers are mounted for the reason aswill be described later, and FIG. 10 shows the first balancer of them.

A first balancer 9 is constructed by providing a projected part 93 whichacts as a balancer at one side of a cylindrical body 92 having a fittinghole 91 to the main shaft 7. A flange portion 94, which forms a thrustsurface, is formed at one end of the cylindrical body 92.

The first balancer 9 is fitted onto the main shaft 7 between the rotor22 of the motor 2 and the upper fixed scroll 33 with the flange portion94 at the lower side so that the first balancer 9 acts as an upperbalancer of the compressor.

The first balancer 9 functions as a balancer for the compressor andfurther functions to position the rotor 22 of the motor 2 in the axialdirection by setting the length of the cylindrical body 92. The flangeportion 94 at the lower end portion forms a thrust surface and abuts onthe upper surface of the fixed base plate of the upper fixed scroll 33so that it receives the entire weight of the main shaft 7 and the rotor22 here to be rotated.

FIG. 11 shows the construction of a second balancer 78, and theeccentric thickness portion 78, which acts as a balancer, is formed orfitted on a peripheral surface of the oil feed pump 76 shown in FIG. 1over the entire length of the oil feed pump.

Specifically, the thickness of the sidewall of the oil feed pump 76 isformed to be partially thick by decentralizing the pump inside andoutside diameter along the rotary shaft.

By constructing like this, imbalance rotation is made, and the secondbalancer is given the function of both the oil feed pump and the lowerbalancer of the compressor.

The eccentric amount can be made small by forming the balancer over thesubstantially entire length of the oil feed pump 76. Therefore, evenwhen the eccentric portion is immersed in the oil and rotates, agitationloss of the oil by the eccentric portion can be restrained to theminimum.

FIG. 12 explains an operational effect of the second embodiment. Inorder to cancel the imbalances of the orbiting scroll, the firstbalancer B1 and the second balancer B2 are normally disposed at one endside of the main shaft 7 as shown in the drawing (a) to keep dynamicbalance and static balance. Each balancer is usually mounted to the endring of the motor rotor, which is fixed to the main shaft 7, by shrinkfitting.

Balancing is set so that Fc=Fc1−Fc2, Fc1×L1=Fc2×L2 as is known.

However, when the orbiting scroll 31 and the fixed scrolls 33 and 34contact each other at the volute teeth, the centrifugal force of theorbiting scroll 31 is all received by the volute teeth of the fixedscrolls 33 and 34. Therefore, the moment Ml occurs to the main shaft 7by the Fc1 and Fc2 as in FIG. 12( b), so that the moment is received bythe upper and lower main bearings 33B and 34C.

As a result, the main shaft tilts and rotates as shown in the drawing,and the main bearings 33B and 34C are easily damaged and worn byso-called one-side abutment.

Thus, as shown in FIG. 12( c), namely, as the second embodiment of thisinvention described above, the two balancers B1 and B2 are disposed atboth sides with the main bearings 33B and 34C therebetween, wherebyoccurrence of moment is eliminated to be able to rotate the main shaft 7in parallel with the main bearing, and bearing reliability can beenhanced.

INDUSTRIAL APPLICABILITY

This invention can be favorably utilized in an air conditioner or an iceheat storage system that are tuned to be normally operated with a lowcompression ratio, or in an air conditioner using a refrigerant such asa CO₂ gas and having a low compression ratio at normal operation.

1. A scroll compressor comprising: a compression section provided in aclosed container, said compression section including an orbiting scrollhaving volute teeth formed substantially symmetrically on both surfacesof an orbiting base plate, and a main shaft being penetrated through andfixed at a center portion of said orbiting scroll and a pair of fixedscrolls opposed to said both surfaces of said orbiting scroll, each ofsaid fixed scroll having volute tooth corresponding to each of saidvolute teeth of said orbiting scroll to respectively form compressionchambers; and a motor provided in said closed container for driving saidmain shaft, and wherein said main shaft has a notch part at a portionpenetrating through said orbiting scroll and fixed scrolls, and a slideris provided, said slider having eccentric hole including a flat slidesurface corresponding to said notch part, said slider being fitted tosaid main shaft where said notch part is formed, and said slider beingmade slidable in a direction orthogonal to a length direction of saidmain shaft by said flat slide surface.
 2. The scroll compressoraccording to claim 1, wherein said closed container is verticallydisposed, said compression section is disposed at a lower portion insaid closed container, said motor is disposed at an upper portion insaid closed container, a lubricating oil storage chamber is formed insaid closed container below said compression section, and an oil feedpump for sucking up a lubricating oil from said lubricating oil storagechamber is disposed at a lower end of said main shaft.
 3. The scrollcompressor according to claim 2, wherein said closed container ispartitioned by said compression section into a motor housing part andthe lubricating oil storage chamber, said suction pipe is provided atsaid motor hosing part, said discharge pipe is provided at saidcompression section, and an oil feed path is formed, said oil feed pathcommunicating from said oil feed pump, running through inside of saidmain shaft, opening at a main shaft bearing of said upper fixed scroll,passing through a main shaft bearing of said orbiting scroll, passingthrough a main shaft bearing of said lower fixed scroll and reachingsaid lubricating oil storage chamber.
 4. The scroll compressor accordingto claim 3, wherein a passage is provided in said compression sectionfor communicating between said motor housing part and said lubricatingoil storage chamber, and a check valve, for preventing backflow of saidlubricating oil, is provided at an opening of said passage at saidlubricating oil storage chamber.
 5. The scroll compressor according toclaim 3, wherein a suction port, for communicating between said motorhousing part and said compression chamber, is provided at an outerperipheral portion of said upper fixed scroll of said compressionsection.
 6. The scroll compressor according to claim 1, wherein saidsuction pipe is provided to said closed container in a vicinity of saidcompression section, and a glass terminal is provided at an upper endportion of said closed container.
 7. The scroll compressor according toclaim 1, wherein seal means is provided at said orbiting scroll forsealing compression chambers formed between said orbiting scroll andsaid fixed scrolls from an orbiting bearing provided at a main shaftside of said orbiting scroll and main shaft bearings provided betweensaid fixed scrolls and said main shaft.
 8. The scroll compressoraccording to claim 7, wherein said seal means is provided at a core partof said orbiting scroll at surfaces thereof facing to said fixedscrolls.
 9. The scroll compressor according to claim 1, whereinbalancers, for canceling imbalance associated with eccentric orbitingmovement of said orbiting scroll, are fitted to said main shaft at bothsides of said compression section.
 10. The scroll compressor accordingto claim 2, wherein a first balancer is provided at said main shaft orsaid rotor of said motor between said compression section and saidmotor, and a second balancer is provided at a lower end portion of saidmain shaft.
 11. The scroll compressor according to claim 10, whereinsaid second balancer is formed integrally with said oil feed pump. 12.The scroll compressor according to claim 1, wherein said notch part ofsaid main shaft is formed to extend through said main shaft bearings ofsaid upper fixed scroll and said lower fixed scroll.
 13. The scrollcompressor according to claim 1, wherein said notch part of said mainshaft composes a part of an oil feed path formed in the bearing.